The present invention concerns a cutting insert, preferably for turning and/or milling, in the form of a polyhedron with at least two substantially parallel main faces each with a polygonal contour and with a peripheral side wall consisting of several side faces which connect the parallel main faces to each other. At the junction of at least some of the partial side faces with at least one of the main faces are formed cutting edges which have a presettable or predefined profile which is defined by the structuring of the upper and/or lower main face and/or of the side faces in the region of the cutting edge.
Corresponding cutting inserts have already been known for a long time. These cutting inserts are typically made of hard metal and are first pressed from powdered material and then sintered and then, if required, also worked subsequently to obtain their final form. Such cutting inserts are distinguished by particular hardness and durability, but on the other hand also have a lower fracture resistance than tool steel and so, to obtain sufficient stability, are restricted with respect to their geometrical design. The fitting of cutting inserts in cutting tools requires corresponding receptacles and supports on the cutting tools, which have certain space requirements, so that the tools must have corresponding dimensions and designs in order, particularly with exchangeable cutting inserts, to offer sufficient space for one or more cutting inserts and for their fastening elements.
Owing to their extraordinary hardness and the quality (dimensional stability and sufficient fracture resistance) of such cutting inserts which has been improved more and more in the course of time, in the meantime they have gained acceptance in broad areas of metal working as the essential cutting elements, but are still relatively expensive both in manufacture and in practical application, i.e. exchange of inserts which is usually associated with stoppage of production.
For this reason, in the past there has been development of cutting inserts which have several independent cutting edges, only one or some of which engage with the work piece during use of a tool, while, after wear of a cutting edge, the cutting insert can be rotated or turned in the tool in order then to engage with the work piece with a new, unworn cutting edge. It goes without saying that, the more usable cutting edges a given cutting insert has, the more economical it is.
But also essential for the durability of cutting inserts and the performance of cutting tools is the concrete fitted position and support of the cutting inserts on stop faces which are intended to offer support for the cutting insert on as large a surface area as possible, without damaging the non-active cutting edge sections in the process, and with a geometrical arrangement, which transmit the cutting forces arising at the active cutting edge substantially in the form of pressure forces to the tool, and if possible are not intended to act in the form of bending forces on the cutting insert.
In tools which are to be equipped with several cutting inserts, e.g. in milling tools, the concrete geometry and fitted position of the cutting inserts moreover plays in this respect a substantial role as they are to be simple and easy to assemble and yet, to obtain high performance and to reduce the wear and down times, as large as possible a number of cutting inserts are to be accommodated with a correspondingly narrow distance between adjacent cutting inserts on such a tool.
In this case, in practice many concrete operations of machining work pieces require only the production of fine shallow structures or the removal of only a slight excess size on a concrete work piece. For instance, camshafts of which the central shaft section consists of a relatively thin-walled tube on which the cams are mounted have in the meantime been developed for motor vehicle engines. For reliably fastening the cams to the tube, relatively flat grooves must be formed in the outer wall of the tube. This can be done, for example, as in the traditional manufacture of camshafts, by means of side-milling cutters which at their outer circumference are equipped with corresponding cutting inserts for forming such grooves.
The present invention is particularly suitable for such applications. Traditionally, corresponding grooves were made with so-called grooving inserts, or grooving plates which in general have only one or two cutting edges. Such plunging plates are difficult to fit and should be exchanged for new plunging plates frequently due to their small number of cutting edges.
Compared with this state of the art, it is the object of the present invention to provide a cutting insert and corresponding cutting tools which prove to be particularly favorable for forming shallow structures.